Detecting and tracking change has several important applications in dentistry. These include monitoring for bone loss in the jaw, monitoring adolescents for the cessation of growth (a pre-requisite for some procedures), and patient education in several fields including orthodontics.
Loss of bone density in the upper and lower jaws is a common occurrence in a wide range of dental patients and can cause severe problems ranging from tooth loss to infection. Causes for bone loss include extracted teeth, poor or misaligned bridge work, trauma and naturally occurring misalignment as well as other factors that prevent the root structures connecting teeth to jaw from being properly stimulated.
Bone loss becomes more likely as a patient ages and is extremely common, especially in specific patient groups. It is also is an early indicator of osteoporosis, a condition which afflicts a large portion of the population, especially older women, and thus has relevance beyond the direct implications for dental health. Finally, the onset of bone loss can be quite sudden in some circumstances, progressing rapidly in a matter of months. The condition can be checked if identified, but cannot be reversed. Left unchecked, the consequences are extreme. These considerations, combined with the prevalence of the condition, make monitoring all adults for dental bone loss an important preventive measure. If identified early, a number of measures can be taken to slow or stop bone loss, as well as to repair damage and related conditions before they can spread or worsen.
In general, patients experiencing bone loss are not aware of the condition until they are informed of it by their dentist. Generally this happens only after the bone loss has progressed significantly. Bone loss can also begin and progress rapidly, making this general lack of awareness all the more problematic.
A number of technologies exist for monitoring patients for jaw bone loss. For example, MRI and CT scans are sometimes used to assess bone loss. However, these procedures rely on large, expensive and specialized devices and are not practical in most dental office settings. For these and other reasons, common practices generally rely on far simpler techniques, specifically periodontal probing or manual (unassisted) comparison of x-rays.
By way of summary, common methods for identifying bone loss in patients include:                1. Periodontal probing—measuring of the depth of pockets around the teeth with a small probe marked off like a ruler;        2. Examining dental x-rays, either singly or in side-by-side manual comparison with similar x-rays; and        3. Assorted approaches relying on specialized equipment or procedures, including:                    a. MRI (Magnetic Resonance Imaging);            b. CT (Computerized Tomography) Scan; and            c. Biopsy (to assess bone density).                        
Each of these methods has a number of short-comings, however. For example, using probes requires careful and systematic checking across the mouth at regular intervals, and can be both time consuming and unreliable. It is also imprecise, and does not lend itself to documentation or tracking X-rays are often difficult to compare due to differences between images arising from parallax, image rotation, image framing or other factors. Tracking changes in jaw bone volume or density using x-ray comparison is time-consuming and error-prone, especially if differences arising from how the images are captured introduce subtle differences not attributable to bone loss. Finally, neither periodontal probing nor x-ray comparison is effective in patient education, as probes provide little in the way of visual aids, and x-rays can be difficult for lay people to understand and even more so to compare. Patient education is an important consideration, as the effects of bone loss are often not evident to the patient, and motivating patients to change behaviors immediately is important in heading off progression.
New techniques are desired that address the problems described above by allowing dentists to identify, assess and monitor bone loss and other forms of change over time using historical or new dental x-rays as a baseline in a cost-effective manner, or which allow dentists to educate patients by creating visual aids. The present invention addresses these needs in the art.